• Journal of Korean Neurosurgical Society
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• 제62권6호
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• pp.712-722
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• 2019

Objective : Although magnetic resonance guided focused ultrasound (MRgFUS) has been used as minimally invasive and effective neurosurgical treatment, it exhibits some limitations, mainly related to acoustic properties of the skull barrier. This study was undertaken to identify skull characteristics that contribute to optimal ultrasonic energy transmission for MRgFUS procedures. Methods : For ex vivo skull experiments, various acoustic fields were measured under different conditions, using five non-embalmed cadaver skulls. For clinical skull analyses, brain computed tomography data of 46 patients who underwent MRgFUS ablations (18 unilateral thalamotomy, nine unilateral pallidotomy, and 19 bilateral capsulotomy) were retrospectively reviewed. Patients' skull factors and sonication parameters were comparatively analyzed with respect to the cadaveric skulls. Results : Skull experiments identified three important factors related skull penetration of ultrasound, including skull density ratio (SDR), skull volume, and incidence angle of the acoustic rays against the skull surface. In clinical results, SDR and skull volume correlated with maximal temperature (Tmax) and energy requirement to achieve Tmax (p<0.05). In addition, considering the incidence angle determined by brain target location, less energy was required to reach Tmax in the central, rather than lateral targets particularly when compared between thalamotomy and capsulotomy (p<0.05). Conclusion : This study reconfirmed previously identified skull factors, including SDR and skull volume, for successful MRgFUS; it identified an additional factor, incidence angle of acoustic rays against the skull surface. To guarantee successful transcranial MRgFUS treatment without suffering these various skull issues, further technical improvements are required.

• Animal Systematics, Evolution and Diversity
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• 제37권3호
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• pp.205-211
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• 2021

This study investigates the morphological and skull characteristics of the Siberian weasel Mustela sibirica quelpartis from the Jeju Island, South Korea. A total of 26 roadkill specimens (22 males and 4 females) were collected from October 2012 to April 2016. All collected specimens were examined for morphological characteristics, but only 19 specimens (16 males and 3 females) were in a good enough condition to process for skull measurements. This study showed no significant differences in ear length between male and female (p>0.05), and significant differences were found in head-body length, tail length (TL), and hind-food length (p<0.05). Both the male and female of M. s. quelpartis were larger in its external characteristics except for TL than M. s. coreanus living in the mainland of South Korea. M. s. quelpartis males have a smaller skull size than their female counterparts. In general, both male and female M. s. quelpartis showed external characteristics in line with the Island Rule. The findings of this study are important in order to shed more light on the evolutionary mechanism of small mammals living on the Jeju Island.

• 한국기계가공학회지
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• 제13권2호
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• pp.49-54
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• 2014

Skull Melted 3.2YSZ has good physical properties and does not undergo low temperature degradation. Due to these excellent physical and mechanical properties, Skull Melted 3.2YSZ has been studied for use in dental implants. In this study, a ø2.2mm Initial Twist Drill was made using Skull Melted 3.2YSZ; the drilling characteristics were compared with those of the traditional SUS420J drill. The experimental results indicate that the Skull Melted 3.2YSZ drill requires similar thrust forces and has a slightly higher temperature.

• 대한수의학회지
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• 제34권4호
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• pp.705-714
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• 1994

This study was carried out to identify the craniometric characteristics of the skull of Korean native goat. The results were as follows; The skull index, cranial index, facial index, right orbital index and left orbital index were $55.86{\pm}2.14$, $59.97{\pm}3.68$, $107.03{\pm}5.71$, $92.22{\pm}4.54$and $90.47{\pm}5.48$, respectively. The ratio of facial length to cranial length was 1:1.15 and the ratio of length of cranial base to palatal length was 1:1.35. The skull length was more correlated to the facial length than to the cranial length(p<0.01). The skull width was more correlated to the width between foramina supraorbitales than to the width between foramina infraorbitales. It also showed negative correlation to the medial width between bases of processus cornualis but positive correlation to the lateral width between bases of processus cornualis(p<0.01). The width between tips of both horns showed high positive correlation to the medial width between processus cornualis, but negative correlation to the lateral width(p<0.01).

• Journal of Korean Neurosurgical Society
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• 제30권1호
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• pp.54-59
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• 2001

Objectives : With the advancement of a social life, the pediatric head injuries(PHI) occur greater than ever. Since the PHI differs from adult head injury with regards to mechanism of trauma, prognosis, and mortality, it is important to identify the characteristics of the PHI for its proper treatments and prognosis. Methods : For this study, a series of 365 PHI patients under 15 years of age who were admitted to our hospital, were evaluated from January 1991 to December 1996. The clinical variable studied were age, sex, Glasgow coma score(GCS), causes of trauma, diagnosis, symptoms, associated injuries and Glasgow outcome score (GOS). The characteristics of PHI were evaluated according to presentations of skull fractures, intracranial hemorrhages, associated injuries, GCS at admission and GOS. Results : Mean age of the studied patients was 6.51 years of age. The majority of PHI patients were under the 7 years of age(66.7%). The ratio of male to female was 2.2:1. Seasonally, PHI occurred more frequently during March to August(61.6%). The main causes of the injuries were accidental falls and traffic accidents(47.1% and 46.3%). One hundred ninety seven(54%) patients suffered from skull fractures and 110(30.1%) patients were developed intracranial hemorrhages and acute epidural hematomas(17.8%) which were the most common intracranial hemorrhages. There was statistical significance between skull fractures and intracranial hemorrhage (p=0.032) and between GCS and GOS(p=0.001). However, there was no statistical significance between skull fractures and intracranial hemorrhage(epidural hematomas, subdural hematomas, and intracerebral, intraventricular and subarachnoid hemorrhage)(p=0.061, 0.251 and 0.880). Also there were no significance of prognosis between under the seven and over the 8 years of age(p=0.349). Conclusions : The core management for PHI is prevention from its occurrences. However, when unexpected accident occurs, early diagnosis and treatment for PHI by through examination for associated injuries and other damages even if there is no skull fracture are essential in managing patient's outcome.

• 한국재료학회지
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• 제19권2호
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• pp.115-118
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• 2009

The use of dolomite refractories has increased during the past several years in the manufacturing of clean steel during the stainless steelmaking process. However, at the same time, the use of dolomite refractories has led to what is known as the skull formation. In the present work, to understand the skull formation, the wetting characteristics of dolomite substrates by liquid Fe-19wt%Cr-10wt%Ni alloys in various oxygen partial pressures were initially investigated at 1753K using the sessile drop technique. For comparison, the wetting characteristics of alumina substrates were investigated with the same technique. It was found that the wetting index, (1+$cos{\theta}$), of dolomite is approximately 40% higher compared to those of alumina. In addition, the oxygen partial pressure to generate the surface oxide, which may capture the liquid metal on the refractory surface, for dolomite is much lower than that for alumina. From this study, it was concluded that the use of dolomite is much more closely associated with the skull formation compared to the use of alumina due to the stronger wettability and the surface oxide formation at a lower oxygen partial pressure of dolomite.

• 한국기계가공학회지
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• 제13권1호
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• pp.72-77
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• 2014

3.2YSZ melted by the 'skull melting' method has good physical properties and does not undergo low-temperature degradation. Due to its excellent physical and mechanical properties, skull-melted 3.2YSZ has been developed as a dental implant material. In this study, a porous, resin-bonded diamond wheel was created and its grinding characteristics were compared with those of traditional nonporous wheels using skull-melted 3.2YSZ. The experimental results indicate that the porous, resin-bonded diamond wheel requires less grinding force and power. In addition, the porous, resin-bonded diamond wheel requires a greater degree of roughness.

• 한국방사선학회논문지
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• 제13권5호
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• pp.765-771
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• 2019

Skull X-ray 영상에서 노이즈의 발생은 불가피하며, 이는 영상 화질과 진단 정확도를 저하시키고 디지털 영상 장치의 특성상 오류를 증가시킨다. 이러한 노이즈는 선량을 증가시키면 쉽게 감쇠되긴 하지만 환자가 받는 피폭선량이 더 큰 문제를 야기할 수 있다. 그래서 선량문제를 해결하고 동시에 노이즈를 줄이기 위해저 선량에서 노이즈 감소 알고리즘이 활발히 연구되고 있는데, 초기에 개발되고 널리 사용되어진 median filter와 Wiener filter는 노이즈 감소 효율이 떨어지고 영상경계에 대한 정보가 많이 손실된다는 단점이 있다. 본 연구의 목적은 이전 노이즈 감소효율의 문제점을 보완할 수 있는 total variation (TV) 알고리즘을 skull X-ray 영상에 적용하여 정량적으로 평가하고 비교를 하는 것이다. 이를 위해 Siemens사의 X-ray 장치를 사용하여 성인 skull을 모사할 수 있는 팬텀을 통해 다양한 관전압과 관전류량을 사용하여 실제 skull X-ray 팬텀 영상을 획득하였다. 또한, 각각의 팬텀 영상에 noisy image, median filter, Wiener filter, TV 알고리즘을 적용하였을 때의 대조도 대 잡음비 (CNR)와 변동계수 (COV)를 비교 측정했다. 실험 결과 TV 알고리즘을 적용하였을 때, 모든 조건에서 CNR와 COV 특성이 우수함을 확인할 수 있었다. 결론적으로 이번 연구를 통해 TV 알고리즘을 사용하여 영상의 질을 높일 수 있는지에 대해 확인해 보았고, 이론적으로 CNR 값은 관전류량이 증가할수록 노이즈가 감소함으로 인해 증가하는 것을 알아볼 수 있었다. 반면에, COV는 관전류량이 증가할수록 감소하였으며 관전압이 증가하였을 때 noise는 감소하고 투과량이 증가하여 COV가 감소하는 것을 알아볼 수 있었다.

• Journal of Korean Neurosurgical Society
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• 제30권1호
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• pp.89-94
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• 2001

Skull or brain metastasis from thyroid carcinoma is rare. Between Jan. 1993. and Jan. 2000. the authors experienced 7 cases of skull(4 cases) or brain(3 cases) metastasis from thyroid carcinoma. Clinical characteristics, radiologic findings and pathologic features were analyzed retrospectively. Among 4 cases of skull metastasis, 3 cases were follicular carcinoma and one was papillary carcinoma with follicular variant. All cases of brain metastasis were papillary carcinoma. We treated the patients by combination with surgical resection, radioactive iodine therapy and radiation therapy. Characteristics of skull or brain metastasis from thyroid carcinoma is reviewed with a pertinent literature.

• 한국결정성장학회지
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• 제16권4호
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• pp.141-148
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• 2006

스컬용융법은 생산원가가 낮고 crust의 재사용으로 수율이 좋아 양질의 산화물단결정성장 및 대량생산에 좋은 방법이다. 본 연구에서는 루틸단결정을 스컬용융법에 의해 성장시켰으며, 서로 다른 성장조건에서의 ingot특성을 비교하였다. 좋은 품질의 루틸 ingot 성장을 위한 조건은 직경 12, 높이 14cm 도가니 사용, 3000pF의 tank condenser 용량, 2.84 MHz의 주파수, 9시간의 용액유지시간, 2mm/h의 성장속도였다.